The result leaves the Serie A side in a strong position to advance to the semi-finals in next week's return leg in Turin.
Who else but Ronaldo in the Champions League?
Ronaldo's diving header broke the deadlock on the stroke of half-time, with David Neres equalising within 40 seconds of the restart of the quarter-final.
Showing increasing confidence after eliminating three-time defending champion Real Madrid in the last 16, Ajax produced more chances early on but then let Ronaldo waltz through its defence to head in a cross in the 45th minute.
The teams will now meet again for the return leg in Turin on April 16, with the victor set for a last four clash with either Tottenham or Manchester City.
Lil Nas X 'Old Town Road' (Remix) With Billy Ray Cyrus
The Atlanta rapper Lil Nas X arrives at the ideal timing with his recently released and now remixed single " Old Town Road ". And after the controversy with Billboard , Cyrus tweeted at the rapper, "Been watching everything going on with OTR".
The Juventus defender could have sent it back, safety first, but he tried to control the ball. Bernardo Silva was ruled out ahead of the match, but Pep Guardiola's comments after the game suggest the Portugal man was not seriously injured.
Weapons and fireworks were found, as a large number of fans were arrested for fighting and damaging the Johan Cruyff Arena on Wednesday night.
Police in Amsterdam said they fired a water cannon at football fans "to put out flares and prevent unsafe situations".
Barcelona are the only team left unbeaten in the 2018/19 Champions League.
Juventus manager Massimiliano Allegri was full of praise for De Jong after the game, describing the youngster as the "real source" of Ajax's game.
Sergio Busquets was the previously holder of the record, which is now shared with a player who will occupy the midfield alongside him at the Camp Nou next season.